1. Field of the Invention
The present invention relates to a cathode ray tube, and more particularly, to a panel in a cathode ray tube for displaying an image outside of the cathode ray tube.
2. Background of the Related Art
FIG. 1 illustrates a side view of a related art cathode ray tube with a partial section, provided with a fluorescent film 2 having red, green and blue fluorescent material coated on an inside of a panel 1, and a funnel 3 glass welded to rear of the panel 1 having an electron gun (not shown) sealed in a neck portion 3a thereof. There is a shadow mask 5 adjacent to the fluorescent film 2 coated inside of the panel 1 for selection of a color of electron beams 4 emitted from the electron gun fixed to a frame 6, which is held hung from the panel 1, with a spring 7 fixed to the frame being inserted to a stud pin 8 fixed to a sidewall of the panel 1. And, there is an inner shield 9 fixed to one side of the frame by a fixing spring 10 for protecting the electron beams 4, which travel toward the fluorescent film 2 when the cathode ray tube is operative, against an external earth magnetism, and there is reinforcement band 11 wound on an outer circumference of the cathode ray tube (CRT) for preventing burst of the CRT by an external impact during operation of the CRT. There is decorative graphite (not shown) coated on inside and outside surfaces of the funnel 3. There are two, four, and six polar magnets 12 mounted on an outer circumference of a neck portion 3a for correcting paths of travel of the electron beams 4 so that the electron beams 4 can hit on desired fluorescent materials, exactly. And, there is a deflection yoke 13 on an outer circumference of the neck portion for deflecting the electron beams in a vertical and a horizontal directions.
Accordingly, when a heater built in the cathode (not shown) is heated, electrons are emitted from the cathode by a heat from the heater and voltage differences between the cathode and adjacent electrodes, and the emitted electron beams 4 are accelerated and converged as the electron beams 4 pass through holes of a plurality of electrodes disposed at fixed intervals vertical to a direction of travel of the electron beams starting from the cathode toward the screen in succession, and travel deflected in a vertical and a horizontal direction by the deflection yoke 13 mounted on the outer circumference of the neck portion. The electron beams traveled thus pass through a hole of the shadow mask 5 mounted adjacent to the fluorescent film 2, and hit on a relevant fluorescent material formed on an inside surface of the panel 1 exactly, thereby reproducing an image.
A form of the image on the screen is dependent on inner and outer forms (curvatures) of the panel 1; as shown in FIG. 2A, if the panel has fixed curvatures on inside and outside surfaces of the panel 1, as shown in FIG. 6A, the image formed by lights emitted from the fluorescent material coated on the inside surface of the panel is changed because the curvature becomes greater as a distance of view becomes farther to cause refraction indices of the light passing through the panel 1 to vary with the inside and the outside curvatures. In a structure of a panel 1 which has fixed inside and outside curvatures, since the image is curved by refraction of the lights depending on the curvature during operation of the cathode ray tube, a prolonged watch of the image accelerates eye fatigue because watching such an image is not convenient. And, the outside curvature of the panel 1 acts as a convex mirror, to reflect a large area external lights in various angles, which deteriorates a picture quality and causes blinding and fatigue of the eye. In order to solve these problems and to provide a flat image, the panel 1 is formed to have a flat outside surface and a curved inside surface as shown in FIG. 2B, or to have flat surfaces both in outside and inside of the panel 1. However, in a case of the panel 1 as shown in FIG. 2B which has a flat outside surface and a curved inside surface, the image can not be flat perfectly because the inside curvature is dependent on various conditions of an inside structure.
As shown in FIGS. 5Axcx9c5C, an extent of curve of the image is dependent on a distance of view to the image, i.e., it can be known that the farther the distance, the greater the extent of curve. That is, as shown in FIG. 6C, even though the image is almost planar when the image is seen near to the image, the image is gradually curved as the distance of view becomes the greater.
In the meantime, as shown in FIG. 2C, in the panel 1 with flat outside and inside surfaces, because a view of the image varies with the distance to the image, to be perfectly flat when the distance is adequate as shown in FIG. 6B, and to be concave when the distance is short contrary to above and to be the flatter as the distance becomes the farther, a computer monitor has a problem in that a perfect flat image can not be implemented because the distance of view is short comparatively.
Accordingly, the present invention is directed to a panel in a cathode ray tube that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a panel in a cathode ray tube, which can provide a perfect flat image at an appropriate distance of view.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the panel in a CRT having a flat outside and a curved inside surfaces, wherein a condition of 2.48xc3x97106(mm2)xe2x89xa6Rxc3x97CFTxe2x89xa64.38xc3x97106(mm2) is set for the CRT for use as a TV receiver, where R is a curvature represented by at least one of vertical, horizontal and diagonal curvatures of the inside surface of the panel and CFT is a center thickness of the panel.
In other aspect of the present invention, there is provided panel in a CRT having a flat outside and a curved inside surfaces, wherein a condition of 2.17xc3x97105(mm2)xe2x89xa6Rxc3x97CFTxe2x89xa66.93xc3x97105(mm2) is set for the CRT for use as a monitor, where R is a curvature represented by at least one of vertical, horizontal and diagonal curvatures of the inside surface of the panel and CFT is a center thickness of the panel.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.